An electromagnetic coil gun system includes a launcher and a projectile that is fired from the launcher. The launcher has a barrel with a series of circumferential electrical excitation coils that extend longitudinally along the length of the barrel. The projectile has a circumferential armature near its tail. The projectile is propelled from the gun by producing a traveling sequence of propulsive currents in the electrical excitation coils. A propulsive magnetic field produced by the electrical excitation coils interacts with the armature of the projectile to propel the projectile along the length of the barrel and out of the muzzle end of the barrel. The fundamental principles of the electromagnetic coil gun have been known for some time, see for example U.S. Pat. Nos. 2,235,201; 3,611,783; 4,926,741; and 5,125,321, whose disclosures are incorporated by reference in their entireties.
This basic approach under development is promising in those cases where the projectile is an unguided device that is an inert kinetic slug or that contains essentially no more than a warhead. However, it is expected that with further development the range of the electromagnetic coil gun system will be well beyond the line of sight from the launcher. Optimum performance will be achieved by including a guidance subsystem that guides the projectile after it is fired from the launcher.
The guidance subsystem for the projectile of the electromagnetic coil gun system may be based on any operable type of sensing technology. The guidance may be based on radar, visible light, infrared light, the global positioning system (GPS), or any other approach that survives the high acceleration experienced during the launching of the projectile and provides the necessary guidance commands to a control subsystem. These guidance technologies are all susceptible to erratic behavior or failure as a result of the high-magnetic-field environment, typically 30 Teslas or greater, produced within the launcher barrel during the firing of the projectile. Therefore, care must be taken to protect the sensors, signal processors, and other components of the guidance subsystem from the high magnetic fields produced by the launcher.
One approach to protecting the guidance subsystem is to place magnetic shielding around the guidance subsystem. This approach has the drawback that a sufficient amount of magnetic shielding for the extremely high magnetic fields produced by the launcher must be quite thick and consequently heavy. This weight and volume of magnetic shielding adds kinetic mass to the projectile, but it reduces the size of the warhead that may be used.
There is therefore a need for an improved approach to the design of an electromagnetic coil gun system to reduce the adverse effects of the high magnetic fields required to propel the projectile. The present invention fulfills this need, and further provides related advantages.